Evidence for Rampant Homoplasy in the Phylogeny of the Epiphyllous Liverwort Genus Cololejeunea (Lejeuneaceae)

Rampant homoplasy can be a major challenge in the classification of land plants that have limited morphological differences and/or ecological diversity, such as liverworts and mosses. Here we present the first comprehensive molecular phylogeny of the derived liverwort genus Cololejeunea and its close relatives. We used three markers (trnL-F rbcL, and nrITS) and 116 accessions representing the geographic range as well as the morphological diversity of this predominantly epiphyllous genus. The molecular data support three major lineages: Colura, Myriocoleopsis, and Cololejeunea. Myriocoleopsis species were resolved in a clade with Cololejeunea minutissima. Aphanolejeunea and Chondriolejeunea were both resolved as putative monophyletic groups, and nested in the Cololejeunea clade. Cololejeunea angustiflora was found to be sister to the clade comprising the remaining Cololejeunea species. Currently accepted subgenera of Cololejeunea were paraphyletic or polyphyletic. Six out of 30 species with multiple accessions were not supported as natural taxa. The current classifications of Cololejeunea have been influenced by frequent homoplasy of morphological characters and do not accurately reflect species relationships. A new classification for this genus is outlined. Our data did not provide evidence for ancient vicariance events where major clades and continents are associated, instead some evidence was recovered for recent intercontinental species range expansion.